A look into Grisha's memories shows Eren the many secrets his father was hiding, including one which led to his mother's demise.
That's the only proper state
of mind for living things.
تلك هي الحالة الذّهنيّة الوحيدة 
.الّتي تناسب الكائنات الحيّة
Das ist die normale Geistesverfassung
eines jeden Lebewesens.
Credo che sia questa la mentalità normale
per ogni essere vivente.
Ведь так и поступают все живые существа.